Model Discussion - 16th January

[gottolovethisweather]

Synoptically there is not far for the cold air mass boundaries to change for during the next few runs to leave us in the cold air.

And I think that everything will be a little further west as the negative zonal mean anomalies put a stop on the eastward flow.

Just for FUN, at T+192:

Reminds me of Dads Army. So close for the south.

You are such a tease Chinio.

The floodgates should certainly be opened in the not so distant future and to my mind, one question remains.

From which direction, will the Dad's Army battalions be attacking us?

At this stage, come t+120 and beyond, I would hedge my bets at say, 60% in favour of the north west, 30% in favour of the north east and only 10% likelihood a south western air mass attack.

I am most definitely looking forward to the next few runs from all the various models.

Regards

gottolovethisweather

Edited January 16, 2012 by gottolovethisweather

[weathe20]

Guys a will take a large slice of PTB 1 to go please-

http://modeles.meteo...-1-1-150.png?12

OR 5

http://modeles.meteo...-5-1-162.png?12

OR 7

http://modeles.meteo...-7-1-144.png?12

OR 11

http://modeles.meteo...11-1-156.png?12

Or 15

http://modeles.meteo...15-1-180.png?12

Or 18

http://modeles.meteo...18-1-180.png?12

Remember the prediction ENSEMBLE MEAN to -8c for londres on the 23rd

The GFS is edging west every run!

S

Sure is >

[danm]

GFS at 144 we are so close to a cold easterly:

...but it doesn't quite reach us. But if you compare this chart with the corresponding chart from the GFS 6z (below), we are closer to being affected by that easterly. As Nick Sussex said, the PV is more elongated, and that pesky low sitting over southern Greenland has more energy going north rather than east compared to the 6z. As a result the easterly edges a little closer, and we see more ridging of heights towards Svalbard from the Russian high. If we can see the PV back a little further west, and if the low over S. Greenland continues to see energy diverted north, rather than east (i.e become less flat) then that gives us a greater chance that the easterly will reach our shores on the GFS.

Here is the GFS 6z for the same time to compare:

Plenty of potential out to 144 on the GFS. Whether that potential will translate to an outcome remains to be seen.

Edited January 16, 2012 by danm

[❄️❄️❄️❄️❄️❄️❄️❄️❄️]

Remember the prediction ENSEMBLE MEAN to -8c for londres on the 23rd

Nope.

-6 at its coldest.

[phil nw.]

We will have to see what the ECM shows later but to me the GFS and UKM are pretty close out to T144hrs..showing a colder NW flow but with the deeper cold just to our east.

http://www.meteociel...44-21.GIF?16-17

http://modeles.meteo...12-0-144.png?12

That Azores high is still reluctant at this stage to move far enough away to allow that trough from Scandinavia to disrupt further west which would bring the cold to us.

It`s a close thing on these runs with the Atlantic just strong enough to hold back anything from the east just now.

It`s worth watching for further vortex disruption over Greenland/Iceland -if things react as the background factors suggest.

We are looking for the jet to buckle some more as it loses energy from the weakening vortex.

As it continues to disrupt and throw more shortwaves south east there`s more opportunity for one of these to undercut the block to our north east.Something like this

http://modeles.meteo...12-5-192.png?12

That is at the end of the HR part of the run but if the GFS is shown to be over progressive then this could happen sooner.

Things are finally balanced so the slightest change in the amount of energy from upstream will have a big influence on the temperatures for our little island.

Edited January 16, 2012 by phil n.warks.

[Zakos]

This animation illustrates the pattern change very well - http://policlimate.com/weather/current/gfs_mslp_natl.html

Low heights over Greenland and Arctic right now -http://policlimate.com/weather/current/gfs_mslp_natl_1.png

Heights rise significantly by the end of the run despite us missing out on the cold on this run.http://policlimate.com/weather/current/gfs_mslp_natl_65.png

[BLAST FROM THE PAST]

Indeed HD, yet another close but no cigar run from GFS, but we've seen cold weather remain tantalising close to our E/NE on many occasions in the past - tapping into it is a different proposition altogether though. On

the plus side however it is at least likely to be in situ come this time next week, which is not something we've been able to say hitherto this Winter, so all is far from lost re Feb at this stage.

You have just completely written the rest of Jan off. The way the GFS has and is coming round and the amplification we are seeing 120 then I may suggest that not all is lost for the last 7/8 days of Jan either? UKMO could develop onto deep cold and I think Old met man mentioned earlier, the SW following just south of Greenland would IMO either quickly get absorbed SE ward into first trough or IMO just not develop into anything and just not be there as we get neartime.

BFTP

[shedhead]

You have just completely written the rest of Jan off. The way the GFS has and is coming round and the amplification we are seeing 120 then I may suggest that not all is lost for the last 7/8 days of Jan either? UKMO could develop onto deep cold and I think Old met man mentioned earlier, the SW following just south of Greenland would IMO either quickly get absorbed SE ward into first trough or IMO just not develop into anything and just not be there as we get neartime.

BFTP

I have not completely written the rest of Jan off, I'm simply suggesting Feb offers the greater potential. My earlier post talked about little change across the hi res part of the run, which ends on the 24th and still leaves a week of Jan to go.

[Duane S.]

For me a great set of 12z charts (still awaiting the start of the ECM run, hoping for a good one too).

Strange how we all see things differently though. Some people only seem to see the end results of a model run, i.e. if that run verified will it snow, how cold will it be etc etc. I see a tipping point that is very very close to being reached and when it does we will be seeing very different charts. Still expecting more amplification to be fed into the models over the next couple of days and a westward trend

[Cumulonimbus Tower]

NOGAPS is a thing of beauty (to my untrained eye) tonight (For cold fans) and if the ECM follows it to only half the degree it did this morning then they will be shouting Blizzards from the rooftops by 7 pm this evening

[Weather Wizard]

ECM very similar to GFS but doesnt develop the low in the atlantic at 96h

[Matty M]

Think back at what ECM was posting for todays T96hr chart. If its projection today occurred, it would have

been horribly wrong with its forecast over the last week and the GFS would be shown to have had a much

better handle on things.

I think the GFS OP has performed best out to T144 recently, although that doesn't mean it has been good

mind you! But some other models have really been shown up.

Although i think it is swings and roundabouts.

Edited January 16, 2012 by Matty M

[Matty M]

Again focus on the ECM towards T144hrs where there is the possibility of ridging to Greenland again as hopefully the trough north of UK at T120 heads south into Europe.

I think our best hope going forward is to forget about this weak attempt at an easterly feed within T120

Edited January 16, 2012 by Matty M

[Cecil Hogmanay Melchett]

ECM doesnt look good at 96 and 120h does it.Im not sure there will be snow at all at the end of the week according to this run the cooler uppers are swept away by saturday across eng and wales.

[ukpaul]

Suddenly ECM throws in a complete outlier (as of 120h) and mucks up its consistency!

A totally different chart than all the other models (including GFS).

[Matty M]

ECM doesnt look good at 96 and 120h does it.Im not sure there will be snow at all at the end of the week according to this run the cooler uppers are swept away by saturday across eng and wales.

Im optimistic about the pattern post T120hrs though.

Maybe todays ECM won't show the extent of ridging at T144hrs we wish but i think it may edge towards it.

[Weather Wizard]

Suddenly ECM throws in a complete outlier (as of 120h) and mucks up its consistency!

A totally different chart than all the other models (including GFS).

Actually it looks very similar to the GFS

[Matty M]

Suddenly ECM throws in a complete outlier (as of 120h) and mucks up its consistency!

A totally different chart than all the other models (including GFS).

If people followed the ECM postage stamps in the last 24-48 hours the charts shown on the 12z will not come as a surprise, the majority of ECM Ensembles were showing charts like this this morning

[Cheese Rice]

Not much else to comment on the models from yesterday, as long as the high builds to our east we can tap into colder air, as is evident on the GFS output where an easterly is very close. Mid term seems the best place to look for any cold incursions from the east, not long term.

Interestingly BBC forecast suggest 'it could turn colder at the end of the week'

food for thought?

[Cecil Hogmanay Melchett]

Im optimistic about the pattern post T120hrs though.

Maybe todays ECM won't show the extent of ridging at T144hrs we wish but i think it may edge towards it.

ECM looks a dogs dinner at 120h until we somehow can see the azores high displaced west and the pv get a life and back west its just going to be frustration methinks.

[ukpaul]

Actually it looks very similar to the GFS

For comparison -

ECM 12z @ 120h

GFS 12z @ 120h

Similar? I'd say so with the new JMA but that and ECM seem to go hand in hand at the moment.

Edited January 16, 2012 by ukpaul

[SLEETY]

ECM doesnt look good at 96 and 120h does it.Im not sure there will be snow at all at the end of the week according to this run the cooler uppers are swept away by saturday across eng and wales.

The gfs looks better in that time frame now lol,and Ecm appears to be backtracking.This is going to run and run all week now I think.The uk met has been the most consistent in this it seems and a great run by nogaps,but not sure how high it rates in the credibility stakes?

[Matty M]

ECM T144hrs, definitely something to build on, if not overwhelmingly great.

[Geordiesnow]

ECM doesnt look good at 96 and 120h does it.Im not sure there will be snow at all at the end of the week according to this run the cooler uppers are swept away by saturday across eng and wales.

You got to remember any polar airmasses come from the west are more moderated than they would be if they came off the East due to the lack of land so whilst there may be some wintry showers, snow will be restricted alot.

I think we have now all but seen the ECM doing an complete backtrack from its output 3 days ago of a successful ridge into Greenland and it goes to show how much a ridge is important, it barely devlops one and the pattern is starting to look alot flatter like the GFS constantly predicted until yesterday.

Things can still change but I think theres an overexcitment on a output that does not really hint at anything cold enough for snow, the continent is mild due to the persistance of the Russian high, our side of the Arctic is also very mild for this very reason and as in December, i'm struggling to find where any meaniful cold will come from unless the pattern changes. And of course more importantly the ECM in particular is hinting at some sort of PV, perhaps not as strong as it once was but it has not really weakened has it?

[chionomaniac]

This type of run could be worse in the short term, but with the main body of the polar vortex over the Canadian segment reducing, in the long term it could lead to something better. As ever we are about to find out!